What is Down syndrome?

Down syndrome is a common chromosomal condition causing growth delays and mild-moderate intellectual disability.

It is a congenital condition, meaning it is present at birth.

Down syndrome is also known as 'trisomy 21' as it involves the presence of an extra copy of chromosome 21. It is named after Dr John Langdon Down who identified the condition.

People with Down syndrome usually have mild to moderate intellectual impairment. This can lead to learning difficulties and may include a delay with the development of speech and language.

People with Down syndrome can have distinctive physical features, such as:

• small head, ears and mouth
• upward slanting eyes
• low muscle tone
• short stature (height)
• extra skin on the back of their neck
• outer ear anomalies (differences in appearance)
• flat facial profile (side view)

People with Down syndrome are unique individuals and do not all have the same physical appearance or level of disability.

What medical complications might come with Down syndrome?

About 1 in every 2 babies born with Down syndrome will have heart problems and approximately 1 in 10 will have gastrointestinal (gut) problems.

Hearing and vision problems are also more common in people with Down syndrome. Obstructive sleep apnoea is also common in people with Down syndrome.

Down syndrome is a life-long condition. The extra chromosome 21 can't be removed from your cells.

Down syndrome is the most common reason for someone to have an intellectual disability. The level of disability varies from mild to moderate.

Each person with Down syndrome has a unique experience. It's hard to tell how much a baby with Down syndrome will be affected as a child or an adult.

Some people with Down syndrome can speak quite clearly. Others need to have speech therapy to help them communicate.

If you have Down syndrome, you will have goals in life, just like everyone else. People with Down syndrome need extra support to do things like:

• find a place to live
• find work and contribute to their community
• develop to their full potential

Many of the health issues that people with Down syndrome have can be treated. Frequent health checks can ensure that any problems are detected as early as possible.

In recent times, support for people with Down syndrome has improved, through:

• medical advancements
• progress in social science
• better health care
• better education
• more employment opportunities

Accessing support services, especially early in life, will help your child with Down syndrome improve their physical and mental abilities.

All children learn and develop at their own pace. However, there are effective early intervention programs for children with Down syndrome that can help them reach their full potential.

Some people with Down syndrome can live an ordinary life with a bit of help. The most important thing that babies and children with Down syndrome need is a loving, secure environment in which they feel nurtured and supported.

A person with Down syndrome can expect to live to around 60 years of age.

Down syndrome is caused by abnormalities with how your cells divide in early development. Inside the cells of our bodies are tiny packages called 'chromosomes' that carry genes to determine how we develop.

Most people have 23 pairs of chromosomes in each of their cells. In people with Down syndrome these pairs don't divide correctly, resulting in an extra copy of chromosome 21. This means your cells have 47 chromosomes instead of 46, and this impacts physical and mental development.

There is no known reason why the chromosomes divide incorrectly. It occurs by accident at conception (when the egg is fertilised by the sperm), not because of anything you or your parents have done.

Although the chance of having a child with Down syndrome increases with the age of the mother, anyone can have a baby with Down syndrome.

Down syndrome affects about one in every 1,000 babies in Australia. There are over 15,000 people in Australia living with Down syndrome, across all ethnic and social groups.

Screening tests for Down syndrome are offered to parents during pregnancy. Screening tests can show if your baby is at increased risk of having Down syndrome.

The most common way to screen for Down syndrome is to have the combined first trimester screening. This involves a blood test and an ultrasound scan.

There is also a newer blood test called non-invasive prenatal testing (NIPT). These tests have a high level of accuracy.

Diagnosis before birth

If your screening tests show that there is a high chance that your baby has Down syndrome, you can get a diagnostic test. For the diagnostic test your doctor will test a sample of the placenta or the amniotic fluid.

Diagnosis after birth

A chromosomal condition may be detected at birth or during early childhood. Your doctor or midwife might suspect Down syndrome if your baby or child has the typical physical features. In this case a genetic test can be performed on a small sample of your baby's blood to confirm the diagnosis.

Early diagnosis

Early diagnosis can help your doctor check for complications. Some people born with Down syndrome may need surgery to repair heart defects or gut blockages.

Medicines to treat thyroid disease may also be needed.

There is currently no way to cure Down syndrome. Testing during pregnancy allows you and your family to make informed decisions, including ending the pregnancy.

For this reason, it's a good idea to think about why you are choosing to have the test, and how you will feel once you get the results.

Down syndrome affects about 1 in every 800 babies around the world. It happens by accident and there is not a way to prevent it.

Your doctor or midwife will be able to answer any questions about testing for Down syndrome during your pregnancy.

Down Syndrome Australia has information and services available to parents. They can help you to connect with other parents of a child with Down syndrome.